In recent years, with the development of technology, efficiencies of electronic devices are enhanced accordingly. However, the improved performances of electronic devices are not the only factor that can increase the demand of consumers for the electronic devices. For example, developers have designed a tablet computer for being demountably combined with a keyboard to have multiple kinds of using conditions. Thus, users can adjust current using conditions of the tablet computers according to actual requirement. For example, the combination of tablet computer and keyboard can be adjusted to flip over to function as a tablet or a laptop computer, and thus the current using condition is suitable for users to operate them. In addition, some developers have improved the appearances of electronic devices for attracting consumers to purchase the electronic devices with a more aesthetic design.
According to the above description, it is understood that developers have been trying to increase the desire of consumers to purchase the electronic devices. However, the foregoing manners are not effective enough to attract consumers to purchase their products. Hence, developers have been developing other designs to increase the demand for their products.